package yyl.example.basic.codec;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

public class Escape {

	private final static String[] hex = { "00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "0A", "0B", "0C", "0D",
			"0E", "0F", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "1A", "1B", "1C", "1D", "1E", "1F", "20",
			"21", "22", "23", "24", "25", "26", "27", "28", "29", "2A", "2B", "2C", "2D", "2E", "2F", "30", "31", "32", "33",
			"34", "35", "36", "37", "38", "39", "3A", "3B", "3C", "3D", "3E", "3F", "40", "41", "42", "43", "44", "45", "46",
			"47", "48", "49", "4A", "4B", "4C", "4D", "4E", "4F", "50", "51", "52", "53", "54", "55", "56", "57", "58", "59",
			"5A", "5B", "5C", "5D", "5E", "5F", "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "6A", "6B", "6C",
			"6D", "6E", "6F", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "7A", "7B", "7C", "7D", "7E", "7F",
			"80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "8A", "8B", "8C", "8D", "8E", "8F", "90", "91", "92",
			"93", "94", "95", "96", "97", "98", "99", "9A", "9B", "9C", "9D", "9E", "9F", "A0", "A1", "A2", "A3", "A4", "A5",
			"A6", "A7", "A8", "A9", "AA", "AB", "AC", "AD", "AE", "AF", "B0", "B1", "B2", "B3", "B4", "B5", "B6", "B7", "B8",
			"B9", "BA", "BB", "BC", "BD", "BE", "BF", "C0", "C1", "C2", "C3", "C4", "C5", "C6", "C7", "C8", "C9", "CA", "CB",
			"CC", "CD", "CE", "CF", "D0", "D1", "D2", "D3", "D4", "D5", "D6", "D7", "D8", "D9", "DA", "DB", "DC", "DD", "DE",
			"DF", "E0", "E1", "E2", "E3", "E4", "E5", "E6", "E7", "E8", "E9", "EA", "EB", "EC", "ED", "EE", "EF", "F0", "F1",
			"F2", "F3", "F4", "F5", "F6", "F7", "F8", "F9", "FA", "FB", "FC", "FD", "FE", "FF" };
	private final static byte[] val = { 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x00, 0x01, 0x02, 0x03,
			0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F,
			0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F, 0x3F };

	public static String escape(String s) {
		StringBuffer sbuf = new StringBuffer();
		int len = s.length();
		for (int i = 0; i < len; i++) {
			int ch = s.charAt(i);
			if (ch == ' ') { // space : map to '+'
				sbuf.append('+');
			} else if ('A' <= ch && ch <= 'Z') { // 'A'..'Z' : as it was
				sbuf.append((char) ch);
			} else if ('a' <= ch && ch <= 'z') { // 'a'..'z' : as it was
				sbuf.append((char) ch);
			} else if ('0' <= ch && ch <= '9') { // '0'..'9' : as it was
				sbuf.append((char) ch);
			} else if (ch == '-' || ch == '_' // unreserved : as it was
					|| ch == '.' || ch == '!' || ch == '~' || ch == '*' || ch == '\'' || ch == '(' || ch == ')') {
				sbuf.append((char) ch);
			} else if (ch <= 0x007F) { // other ASCII : map to %XX
				sbuf.append('%');
				sbuf.append(hex[ch]);
			} else { // unicode : map to %uXXXX
				sbuf.append('%');
				sbuf.append('u');
				sbuf.append(hex[(ch >>> 8)]);
				sbuf.append(hex[(0x00FF & ch)]);
			}
		}
		return sbuf.toString();
	}

	public static String unescape(String s) {
		StringBuffer sbuf = new StringBuffer();
		int i = 0;
		int len = s.length();
		while (i < len) {
			int ch = s.charAt(i);
			if (ch == '+') { // + : map to ' '
				sbuf.append(' ');
			} else if ('A' <= ch && ch <= 'Z') { // 'A'..'Z' : as it was
				sbuf.append((char) ch);
			} else if ('a' <= ch && ch <= 'z') { // 'a'..'z' : as it was
				sbuf.append((char) ch);
			} else if ('0' <= ch && ch <= '9') { // '0'..'9' : as it was
				sbuf.append((char) ch);
			} else if (ch == '-' || ch == '_' // unreserved : as it was
					|| ch == '.' || ch == '!' || ch == '~' || ch == '*' || ch == '\'' || ch == '(' || ch == ')') {
				sbuf.append((char) ch);
			} else if (ch == '%') {
				int cint = 0;
				if ('u' != s.charAt(i + 1)) { // %XX : map to ascii(XX)
					cint = (cint << 4) | val[s.charAt(i + 1)];
					cint = (cint << 4) | val[s.charAt(i + 2)];
					i += 2;
				} else { // %uXXXX : map to unicode(XXXX)
					cint = (cint << 4) | val[s.charAt(i + 2)];
					cint = (cint << 4) | val[s.charAt(i + 3)];
					cint = (cint << 4) | val[s.charAt(i + 4)];
					cint = (cint << 4) | val[s.charAt(i + 5)];
					i += 5;
				}
				sbuf.append((char) cint);
			}
			i++;
		}
		return sbuf.toString();
	}

	public static void main(String[] args) throws UnsupportedEncodingException {
		String value = "1234 abcd[]()<+>,.~\\";
		System.out.println(value);
		System.out.println(escape(value));
		System.out.println(unescape(escape(value)));

		String enc = "UTF-8";
		System.out.println(URLEncoder.encode(value, enc));
		System.out.println(URLDecoder.decode(URLEncoder.encode(value, enc), enc));

	}

}
